The present invention relates to a paper handling apparatus of the type having a plurality of bins and a chuck unit and a stapler which are movable along the bins, and causing the stapler to bind an end portion of a stack of paper sheets which have been received from a copier or similar image forming apparatus, sorted, and then stacked on any one of the bins.
A copier, for example, is operable with an automatic document feeder (ADF) and a sorter which sorts a plurality of copy sheets associated with each of a plurality of documents in order of page and thereby produces a plurality of sets of copies. More specifically, while the ADF sequentially feeds the documents to a reading section of the copier in order of page, the sorter distributes the resulting copies of each document one by one to bins thereof. A paper handling apparatus capable of automatically stapling stacks of paper sheets each being distributed to respective one of bins in order of page is disclosed in Japanese Patent Laid-Open Publication (Kokai) No. 57-63561, for example. This kind of apparatus saves time and labor necessary for one to take out the stacks of copy sheets from the individual bins and staple them one by one. In the prior art apparatus, each paper stack is fully pulled out of the associated bin and transferred to an elevatable tray to be stabled there. Another paper stack to be stabled next is pulled out onto the stabled paper stack and stapled there. By such a sequence, a plurality of stapled sets of copies are piled up one upon another. While such a prior art paper handling apparatus allows the stapled copies to be readily taken out, it needs a bulky device for pulling out a paper stack onto the tray and a large exclusive space for the tray, resulting in an increase in cost and in space for installation.
In the light of the above, there has also been proposed a paper handling apparatus capable of automatically stapling paper stacks stored into successive bins without increasing the overall size of the apparatus and the space for installation. This kind of apparatus has a plurality of bins arranged one above another, and a stapler and a chuck unit which are movable up and down along the bins. Paper sheets distributed from a copier or similar image forming apparatus into each bin are gripped together by the chuck unit and then pulled out to such an extent that a portion thereof to be stapled protrude from the bin. In this condition, the end of the paper sheets is stapled and then returned to the original position on the bin. This prior art apparatus, however, has some problems left unsolved, as enumerated below. (1) Paper sheets stacked on a bin are gripped by the chuck unit, pulled out to a stapling position, stapled there, again gripped by the chuck unit, and then returned to the original position within the bin. The stapler and chuck unit, therefore, cannot be shifted to the next bin while the paper sheets are returned into the bin, slowing down the overall stapling procedure. (2) While the stapler and chuck unit are moved from one bin toward another, the chuck unit does not perform the movement for pulling out paper sheets at all. This needs a substantial period of stapling time per bin. (3) When the chuck unit chucks and pulls out paper sheets which are neatly arranged in a bin, it is apt to disturb the stack. Further, it is likely that the neatly arranged stack is disturbed by inertia when pulled out of the bin or by an impact when stopped at the stapling position.